Flame retardation of polymers is currently mandatory for many of their applications in various countries according to certain laws and regulations. Of particular importance are the requirements of polymeric devices, utilized in electrical, electronic and communication systems. In view of the necessity of flame retardancy, a number of systems for flame retardant polymers have been developed. Flame retarding systems usually involve mixing or blending of a polymer with one or more flame retarding chemical additives. Flame retardant compounds based on halogen-containing compounds have been utilized. They are in many cases applied in conjunction with co-additives or synergists such as antimony trioxide. Halogen-based additives can provide reasonable protection from fire hazards. However, some halogen containing compositions suffer from inadequacies and can generate, upon combustion, corrosive hydrogen halides. They also are generally used in relatively high concentration in order to impart flame retardancy.
Metal hydroxides have also been utilized as flame retardants. However, compositions generally require large amounts of the metal hydroxides to be effective for imparting flame retardancy. Metal hydroxides are generally not suitable for developing soft flame retardant thermoplastic elastomer compositions as they can increase specific gravity and can undesirably increase hardness of compositions.
A further method of incorporating flame retardancy into various polymers is to provide a composition with intumescent compounds. According to the principle of intumescence, flame retardant additives form, during the first stages of pyrolysis and combustion, a foamed porous barrier which is substantially impermeable to combustible gasses evolved during pyrolysis and to the molten polymer, prevents their flow to the flaming surface. In addition, it is believed that the intumescent barrier hinders convection of the heat generated in the combustion from entering into the plastic. Additives utilized in intumescent systems can, comprise a “catalyst”, such as ammonium polyphosphate, a char-forming agent, in most cases a polyhydric alcohol, such as pentaerythritol, and a blowing agent using a nitrogeneous material, such as melamine, guanidine or urea, which produce non-combustible gases.
U.S. Pat. No. 5,750,600 relates to a reportedly nonflammable olefin thermoplastic elastomer composition (F) for use in skins of interior automotive trim, which comprises an oil-extended olefin thermoplastic elastomer composition (G), melamine-coated ammonium polyphosphate (h), a specified 1,3,5-triazine derivative, and a lubricant (f), wherein the composition (G) comprises an olefin thermoplastic elastomer composition (D) and a mineral oil (e), the composition (D) comprising 50 to 70% by weight of an ethylene/α-olefin copolymer elastomer (A) having a Mooney viscosity (ML1+4(100° C.)) of 40 to 100, 35 to 21% by weight of a polypropylene resin (B) having a crystal melting point of 140° to 165° C. and an ethylene unit content of 1 to 2% by weight and 15 to 9% by weight of a low-density polyethylene resin (C) having a density of 0.90 to 0.93 g/cm3 and a crystal melting point of 102°-118° C.
U.S. Pat. No. 6,262,161 relates to compositions reportedly having enhanced ignition resistance, comprising from about 5 to about 90 percent by weight of at least one substantially random interpolymers; from about 10 to about 94.9 percent by weight of at least one filler selected from ammonium polyphosphate, magnesium hydroxide, calcium hydroxide, and aluminum trihydrate; and at least one component selected from about 5 to about 50 percent by weight of at least one filler; or about 0.5 to about 20 percent by weight of at least one metal borate, and, optionally, about 0.5 to about 10 percent by weight of at least one processing aid; or about 0.1 to about 15 percent by weight of at least one initiator or at least one coupling agent; or about 0.1 to about 20 percent by weight of at least one hindered amine stabilizer.
U.S. Pat. No. 6,756,440 relates to a reportedly fire resistant resin composition, a method of making the resin composition and an electrical wire comprising the composition. The composition includes a halogen-free propylene resin containing propylene as its main monomer component, a halogen-free styrene-based thermoplastic elastomeric resin modified with an unsaturated carboxylic acid or a derivative of such an acid, and a fire resistant metal hydroxide.
U.S. Publication No. 2006/0084740 relates to a reportedly low-smoke, halogen-free and flame-retardant thermoplastic elastomer. The thermoplastic elastomer includes a polymer having a hydrogenated styrenic/conjugated diene copolymer, an inorganic phosphorus flame-retardant and a flame retardant auxiliary, wherein a weight of the hydrogenated styrenic/conjugated diene copolymer is 50-100 percents of a weight of the polymer, a weight of the inorganic phosphorus flame-retardant is ranged from 0.3 to 2 times of the weight of the hydrogenated styrenic/conjugated diene copolymer, and a weight of the flame-retardant auxiliary is ranged from 0.05 to 0.4 times of the weight of the hydrogenated styrenic/conjugated diene copolymer.
Japanese Publication No. 2003-277573 relates to a non-halogen polymer composition which reportedly has sufficiently high flame retardancy and flexibility, reportedly inhibits blooming of additives to prevent attachment of dust, etc., reportedly has an improved windability by cord reels and is reportedly suitable as a sheathing for a power cord.
International Publication No. WO 2004/044049 relates to reportedly flame retardant plastic resin blends comprising an intumescent flame retardant and at least one plastic resin. Engineering resin blends comprise an intumescent flame retardant and at least one engineering resin. Thermoset resin blends comprise an intumescent flame retardant and at least one thermoset resin. The plastic resin blends and the engineering resin blends are non-halogen. The thermoset resin blends are substantially non-halogen.